Timing device



July 29, 1941. N MILLER 2,250,997

TIMING DEVICE Filed Dec. 14, 1937 \nven-torz. \\hcho\as Miller,

b Wm Hi Attorney.

Patented July 29, 1941 UNITED STATES PATENT @FFICE TIlVIING DEVICEApplication December 14, 1937, Serial No. 179,716

12 Claims.

This invention relates to timing devices, more particularly to devicesfor timing the heating interval of a. heating operation, and it has forits object the provision of an improved device of this character.

More specifically, this invention relates to timing devices of thethermal type, and while it is not limited thereto, it is particularlyapplicable to timing devices of this character for use with electricallyheated devices that are intermittently operated, such as heatingappliances like toasters, wafiie irons and the like; and it contemplatesan improved timing device which measures the cooking period, and whichalso compensates for variations in the ambient temperature of the timingdevice. In other words, it contemplates a thermal timing device whichmeasures substantially the same cooking interval for successive cookingoperations, irrespective of variations in the ambient temperature of thetiming device.

For a more complete understanding of this invention, reference should behad to the accompanying drawing in which Fig. 1 is a perspective view ofa timing device arranged in accordance with this invention, parts beingshown in section so as to illustrate certain details of construction;and Figs. 2, 3 and 4 are diagrammatic representations of the timingdevice of Fig. 1 showing various elements of the timing device indifferent operative conditions.

Referring to the drawing, this invention has beenshown in one form asapplied to a timing device I which is intended to control theenergization of an electrically heated device II, shown diagrammaticallyas an electric toaster. The heating device or toaster I I is providedwith a resistance heating element I2.

The timing device I0 for controlling the toaster II comprises a base I3formed of a suitable electrically insulating material, such as a phenolcondensation product. Provided on the base is an upright support M alsoformed of a suitable electrically insulating material, such as thematerial of which the base I3 is made.

Mounted on one end of the member I4, the

lower end, as viewed in Fig. 1, is a temperature responsive element I5shown as a bimetallic bar.

The bimetal bar I5 is formed of two metals having dissimilarcoeflicients of expansion, and se cured together lengthwise in anysuitable manner, as by welding. The two metals may be Invar and steel,for example. The thermostatic bar I 5 has one end, its left-hand end asviewed in the figures, rigidly secured to the supporting member I4,while its opposite end is free to move in response to changes intemperature.

Also mounted on the support I4 are three resilient switch blades I6, I1and I8 arranged in superimposed relation as shown, and having theirleft-hand ends, as viewed in the figures, rigidly secured to the supportI4, and their opposite ends free to move. The switch arms I6, I! and I8are separated from each other by insulating blocks I3 and 20. Thethermostatic element I5, the switch arms I6, I! and I8, and thesupporting blocks I l, I9 and 2B are all rigidly secured together bymeans of an elongated screw 2I, which passes through apertures (notshown) provided for it in all of these members. Nuts 22 are threaded onthe rod to clamp these, members together. The head of the screw, showndiagrammatically in Figs. 2, 3 and 4, is in direct mechanical andelectrical contact with the bimetallic bar I5, and as shown in Fig. 1the nuts 22 on its opposite end are in direct mechanical and electricalengagement with the upper switch arm I 6. The screw, however, iselectrically insulated from the switch arms I I and I8 in any suitablemanner, as by means of insulating sleeves (not shown) surrounding thesections of the screw that pass through the apertures in these members.

The upper switch arm I6 cooperates with a fixed contact 23 which ismounted on a bracket 24 that in turn is secured directly to the base I3as by means of a screw 25. The contact 23 and bracket 24 areelectrically connected to a binding post 26 mounted in base I3 by meansof a jumper 21. The jumper 21 preferably is mounted on the rear side ofthe base I3 and is connected at its opposite ends to the screw 25 andthe binding post 25.

Thebinding post 25 is electrically connected to one end of a resistanceheater 28 which is in direct thermal relation with the bimetallic barI5. For example, the heater may be, and as shown is, formed in a seriesof turns which are wound about the bimetallic bar. The opposite end ofthe heater 28 is secured directly to the bimetallic bar I5 by means of ascrew 29, and hence, this end is connected through the bimetallic barwith the screw 21 and the upper switch blade I6. This upper switch bladecarries a contact 23a which it biases into engagement with the fixedcontact 23 due to the inherent resiliency of the switch arm.

Mounted on the movable ends of the switch arms I! and I8 are cooperatingcontacts 34] which are normally biased apart by the inherent resiliencyof the two switch arms. The switch arm I I is connected to a lead 3|which, as shown diagrammatically in Figs. 2 to 4, is connected to oneside of the toaster heating element I2. The lower switch arm I8 iselectrically connected with the binding post 26 by means of a jumper 32.The screw 2| and the elements electrically connected with it isconnected to a lead 33 which, as shown diagrammatically in Figs. 2-4, isconnected to one side of an electrical supply source 34. As showndiagrammatically in thesefigures,

end 3"! of the slide member 35.

the opposite side of this supply source is connected to the other sideof the heating element I2.

In view of the foregoing description of the thermostat bar, switch partsand other connections wtih the toaster and the supply source, it will beobserved that if when the elements are in their normal positions shownin Fig. 2 the toaster be connected with the supply source 34, it willnot be energized because the switch contacts 30 are opened. Moreover, itwill'beobserved that the heater 28 is deenergized. However, ifall threeswitch arms I6, IT and I3 are moved downwardly, as viewed in thefigures, from their positions of Fig. 2 to their positions of Fig. 3,the contacts 23 and 23a will be opened and the contacts 30 will be movedinto engagement with .each other. Under these conditions, it will beobserved that the heating element I2. of the toaster is connected to thesupply source 34 in series with the heating element 28 of the thermostatmember I5, and hence, the toaster will be energized, and theheatingjelement 28 will be energized to apply heat to thethermostatic'bar I5.

The switch-elements I6, Il' and I8 are moved from their positions ofFig. 2 to their positions of Fig. 3-by means of a slide member 35mounted to slide in a guideway 35 on the base I3, and having at itsupper end, as viewed in Fig. 1, an overhanging hook-like member 31 whichis arranged to act onthe switch arm I6. Preferably, a saddle 38-madeofsome suitable insulating material, will be mounted on this switcharmhaving a recessed section 39 that receivesthe overhanging This saddlealso has a spacer block 40 interposed between the switch arms I6 and I1.It will be observed, therefore, that when the slide bar. 35 is pulleddownwardly, it will separate the contacts 23- and 23a, and move the twoupper switch-arms I6 and I1 downwardly until the contact 30' on switcharm I'I engages the corresponding contact 30 on theswitch arm I 8,'and'that further downward movement of the slide 35 will move all threeswitcharms downwardly together.

The switch arms are heldgin their position of Fig. 3 against theirnormal tendency to move upwardly by means of a latch 4I made ofinsulating material such as Bakelite, and is pivotally mounted on a: pin42 which in turn is mounted the-base I3. The latch4I is biased in aclockwise direction, as viewed-in the figures, against a stop 44 bymeans of a torsion spring 43. The stop 44 is mounted on the base I3, asshown. The lower end of the latchis received in an elongated aperture 45provided for it in the free end of theswitch arm I1, and it carries anabutment '46, which when the switch arms ,aremoved to their positionsshown in Fig. 3, en-

gages the free end of the switch arm I6 to'hold the switch arms in theirposition of this figure. a

The latch 4| is controlled by the bimetallic thermostat bar I to releasethe upper switch arm I6 when the bimetallic bar has been heated tosubstantially a. preselected high temperature by the heating element '28to. permit the switch arm I6 to move to its initial position of Fig. 2

and as shown in Fig. 4, while the switch arms l1 and 'I8'retain: theircontacts closed, as shown in Fig. 4. When the arm I6 is released, itwill be observed that the. heating element 28 will be shorted out of thetoaster energizing circuit. For the" purpose of controlling the latch 41in this manner, a lever 48 is'mounted on a fulcrum 49 which inturnismounted on a lever 55 pivoted on a pin 5i secured to the base IS. Thelever 43 at its lower end has a loose pivotal connection 52 with thethermostatic bar I5, and at its upper end is arranged to engage anelongated strip-like arm 53. This arm is rigidly secured at itsrighthand end to the latch 4| and its opposite end carries a lateralextension 54 which cooperates with an inclined surface 55 provided onthe upper end of thelever 43. .As shown, the lever 48 has an elongatedslot 49a fitted to the fulcrum so that the lever can move upwardly anddownwardly on the fulcrum as well as rotate about it.

When the slide is drawn downwardly to move the parts to their positionsof Fig. 3 to thereby energize the toaster and the heating element 28,heat will be applied to the thermostatic bar I5 directly from theelement 28. at the same time that the toaster isheating The thermostaticbar I5 is arranged to move downwardly responsivelytoits increase intemperature due to the heat imparted to it, and as it moves downwardly,it causes the inclined edge 55 to move the lefthand endof bar 53'downwardly; this operation rotates the latch 4! in a counter-clockwisedirection, and when the thermostat I5 has been heated to substantially apredetermined high temperature, it will have movedthe latch sufficientlytocause the abutment ltqto release'the switch arm' I6, which thereuponis permitted to return to its initial position shown in Figs. 2 and 4.This operation, as pointedout previously, shorts the heater 28 out ofthe toaster energizing circuit. The switch arms' I1; and. I8, however,are not permitted to moveto their original positions, becausethe lower'end 55. of. the latch engages the free end Ila of the switch arm I! toprevent the return of thesemembers. The parts now occupy their positionsshown in Fig. .4, and even though the heating element 23 is deenergized,the toaster I I remains energized through the switch contacts 35.However, due to the fact that heat has been removed from the bimetal barI5, it begins to cool and to return toward its initial position of Fig.2. As it moves toward this position, itlmoves the inclined edge'55 ofthe lever 48.npwardly so as to permit the arm 53 and latch M to movetoward their positions of Fig. '2

under the influence of the torsion spring 43. When the latch has beenmoved inwardly sufliciently to cause the openingin switch arm I! toregister with the lower end of the'latch, the switch arms are releasedto return to their initial positions of Fig. 2. This opens contacts 30to break the energizing circuit for the heating unit I2 of the toasterII.

In the operation of the device thus far described, it will beunderstood,therefore, that when it is desired to toast a slice 'of bread, the slide35 is operated to move the switch arms from their positions of Fig. 2 totheir positions of Fig. 3 where they are latched by the member M. Thisenergizes the toaster and also the heating element 28. Asthe'temperature of the thermostatic bar I5 rises due to the heatimparted to it, it operates the lever 48 to release the latch M at apredetermined high temperature in so far as the switch arm I5 isconcerned which arm thereupon closes the contacts 23 and 23a toshort-circuit the heater 28.

of the toaster is measured by the heating and cooling periods of thethermostat l5, and that when the thermostat has cut oil the heat to thetoaster responsively to its cooling, it is in condition for an immediatesuccessive operation of the heating device ll.

The basic time interval of the toaster is adjusted by changing theposition of the fulcrum 49 by operating the lever 55]. When this isdone, it will be observed that the position of the inclined surface 55relative to the extension M on the arm 53 is varied. This, of course,varies the intervals of time that the switch parts are held in theirrespective positons of Figs. 3 and 4. In other words, it varies theheating and cooling intervals of the thermostatic bar 15, and hence, itvaries the total toasting time interval.

The strip 53 is formed as a bimetallic element and constitutes a secondthermostat. This thermostat, like the thermostat I5, preferably isformed of two strips of Invar and steel welded together lengthwise. Thethermostat 53 compensates for ambient temperature variations. Thus, asthe ambient temperature varies, the position of the thermostatic bar 95is affected. The effect of the ambient temperature on the bar [5 iscompensated in the member 53. Thus, if the ambient temperature increasesso as to move the bar l5 downwardly, the member 53 likewise movesdownwardly to maintain the same relationship between the elements 54 and55. Conversely, if the ambient temperature is reduced the two elementsmove upwardly to maintain this same relationship.

Thus, whether the timing device be mounted in the cord away from thetoaster, or in the toaster where its ambient temperature is materiallyhigher and varied by the widely varying temperatures in the toaster, thethermostat 53 compensates for the Variations so that the timing intervalmeasured by the timing device remains unchanged. It is only when thelever 50 is adjusted that the basic time intervals is varied.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modifications may be made, and I, therefore, contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire to obtain by Letters Patent of the UnitedStates is:

1. A timing device comprising a thermostatic element, means for heatingsaid thermostatic element, a plurality of switch members for controllinga controlled circuit and said heating means movable to first respectivepredetermined positions in which they energize both said controlledcircuit and said heating means, and said members biased to secondrespective positions in which said circuit and heating means aredeenergized, a latch constructed and arranged to hold said switchmembers in said first position when said latch is in a first position,and when moved to a second position to release one switch member topermit it to move to its second respective position to deenergize saidheating means, and the latch thereafter when returned to said firstposition operating to release the other switch members to permit them toreturn to their said first positions to deenergize said controlledcircuit, a second thermostatic element connecting said firstthermostatic element with said latch so as to move said latch to saidsecond position due to the heating and consequent movement of said firstthermostatic element in one direction, and to return it to said firstposition due to the cooling and consequent movement of said firstthermostatic element in the opposite direction, said second thermostaticelement controlling the action of said first thermostatic element onsaid latch so as to compensate for changes in ambient temperature.

2. A timing device for electric toasters and like heating appliancescomprising a switch arranged when in a first position to close anenergizing circuit for said toaster and when in a second to deenergizesaid toaster, and said switch biased to the second position, athermostatic element, a second switch operable between first and secondcontrolling positions and biased to the second position, meanscontrolled by said second switch when operated to said first positionfor applying heat to said thermostatic element and when operated to saidsecond position to shut off heat from said thermostatic element, amovable latch having a pair of surfaces arranged to engage said switchesrespectively so as to hold them in their first controlling positions,said latch constructed and arranged when moved to one position to removeone surface from engagement with said second switch to release it whilethe other surface remains in engagement with the first switch to hold itin its said first controlling position, and when moved to a secondposition to remove said surface from engagement with said first switchto release it, operable connections between said thermostatic elementand said latch for moving said latch to said first position to releasethe second switch to move to its first position responsive to movementof said thermostatic element when heated whereby heat is shut off fromsaid thermostatic element, and for operating said latch to said secondposition to release said first switch to move to its second controllingposition to deenergize said toaster responsively to movement of saidthermostatic ele ment when it cools.

3. A timing device for electric toasters and like heating appliancescomprising a switcharrange'd when in a first position to close anenergizing circuit for said toaster and when in a second to deenergizesaid toaster, and said switch biased to said second position, athermostatic element, a second switch operable between first and secondcontrolling positions and biased to the second, means controlled by saidsecond switch when operable to said first position for applying heat tosaid thermostatic element and when operable to said second position toshut off heat from said thermostatic element, a latch for holding saidswitches in their first controlling positions constructed and arrangedwhen moved to one position to release the second switch while stilllatching the first switch, and when moved to a second position torelease the first switch, operable connections between said thermostaticelement and said latch for moving said latch to said one position torelease the second switch to moveto its first position responsive tomovement of said thermostatic element when heated so that heat is cutoff from said thermostatic element, and for moving said latch to saidsecond position to release said first switch to move to its secondcontrolling position to deenergize said toaster responsively to movementof said thermostatic element when it cools, said operable connectionsincluding a second thermostatic element modifying the action of saidfirst thermostatic element in moving said latch to said positions so asto compensate for the effects of variations in the ambient temperatureon said first ithermostatic element.

4. A timing device comprising a thermostatic element, first and secondswitches, each operable between first and second controlling positions,

the first switch when operated to its first controlling position closingan energizing circuit for a controlled device and when operated to itssecond for deenergizingsaid circuit, a heater for applying heat to saidthermostatic element energized responsively to operation of said secondswitch to its first controlling position and deenergized resp-onsivelyto operation of said latter switch to its second controlling position,means biasing said switches to their second controlling positions, meansfor manually moving said switches to their first controlling positionsagainst the force of saidbiasing means, a latch constructed and arrangedso that when it is in one position it holds said switches in said firstcontrolling positions, and a second thermostatic element connected tosaid first thermostatic element and :to said latch so as to control themovement of the latch responsively to movement of said firstthermostatic element as it heats and cools, the latch controlled to moveto a second position to release said second switch to move to its secondcontrolling position to deenergize said heater as said firstthermostatic element moves when heated, and to a third position torelease said first switch to move to its second position to deenergizesaid energizing circuit when said first thermostatic element moves whilecooling, the second thermostatic element modifying the action of thefirst on said latch in second for deenergizing said circuit, a heaterfor 3,

applying heat to said thermostatic element energized responsively tooperation of said second switch to its first controlling position anddeenergized responsively to operation of said latter switch to itssecond controlling position, means biasing said switches to their secondcontrolling positions, means for manually moving said switches to theirfirst controlling positions against the force of said biasing means, alatch constructed and arranged when in one position to hold saidswitches in said first controlling positions, a levercontrolling saidlatch operated responsively to. movement of said thermostatic elementwhen heated to move the latch to a second position to release saidsecond switch to move to its second controlling position. to demergizesaid heater, and responsively to movement of said thermostatic elementwhen cooling after said heater has been deenergized to move the latch toa third position to release said first switch to move to its secondcontrolling position to deenergize said energizing circuit, and meansfor shifting the fulcrum of said lever to vary the basictime setting ofsaid timing deviceQ 6. A timing device comprising a thermostaticelement, first and second switches, each operable between first andsecond controlling positions, the first switch when operated to itsfirst controlling position closing an energizing circuit for acontrolled device and when operated to its second for deenergizing saidcircuit, a heater for applying heat to said thermostatic elementenergized responsively to operation of said second switch to its firstcontrolling position and deenergized responsively to operation of saidlatter switch to its second controlling position, means biasing saidswitches to their second controlling positions, means for manuallymoving said switches to their first controlling positions against theforce of said biasing means, a latch constructed and arranged when inone position to hold said switches in said first .controlling positions,a second thermostatic element connected to said first thermostaticelement and to said latch so as to control the movement of the latchresponsively to movement of said first thermostatic element as it heatsand cools, the latch controlled to move to a second positionto releasesaid second switch to move to its second controlling position todeenergize said heater when said first thermostatic.elementmoves whenheated, and to a thirdposition to release said first switch to move toitssecond position to deenergize said energizing circuit when said firstthermostatic element moves while cooling-the second thermostatic elementmodifying the action of the first on said latch in accordance withvariations in ambient temperature, and means for adjusting theconnection between said first and secondthermostatic elements to varythe basic time setting of said timing device.

'7. A timing device for controlling the energizing circuit of anelectrically heated device comprising a bimetallic thermostat bar, aheater for applying heat to said bar, a switch mechanism controllingsaid energizing circuit and heater to energize them and deenergize them,a pivoted latch associated with said switch mechanism to control itsoperationto lat-ch it in itsloperaitive position to energize saidcircuit and. said heater, a lever controlled to said bimetallic bar andsaid latch so that when the bar is. heated it moves the lever to operatethe-latch to effect an operation of said switchv mechanism to deenergizethe heater, whereupon said thermostat bar cools, and when itmoves'responsively to cooling the lever is moved'thereby to operate. thelatch to effect an operation of the switch mechanism to deenergize saidcircuit, a fulcrum for said lever, and means for adjusting the positionof said fulcrum to vary the basic time setting of said timing device.

8. In an electric toaster and like appliance, a thermostatic timingdevice comprising an energizing circuit for the toaster, a bimetallicthermostat, means for applying heat locally to the thermostat, threesubstantially parallel resilient, switch arms, the first biased intoengagement with a fixed contact and the other two carrying cooperatingcontacts and biased apart, the arms arranged so that when the three armsare moved in a respective predetermined direction to predeterminedpositions, the fixed contact is broken by the first arm and the twocontacts on the other two arms are moved into engagement, connectionsbetween said fixed contact, switch arms and energizing circuit andheating means arranged so that when said arms are moved tosaidpredetermined positions, said energizing circuit for the toaster andsaid heating means are energized, a latch for holding said arms in saidpredetermined positions, a lever connected to said latch and saidbimetallic thermostat controlling the movement of said latch so thatwhen the thermostat has been heated to substantially a predeterminedhigh temperature the latch releases said first arm to close said fixedcontact, said electrical connections arranged to deenergize said heatingmeans when said contact is closed, and the lever operating to releasesaid other switch arms to permit them to open their contacts todeenergize said energizing circuit of said toaster when said thermostathas cooled substantially to a predetermined low temperature.

9. In an electric toaster and like heating appliance having anenergizing circuit, a thermostatic timing device comprising a bimetallicthermostat bar, a heater for applying heat to said thermostat barconnected in the energizing circuit, a switch mechanism controlling theenergizing circuit of said toaster and said heater having threesuperimposed flexible switch arms, the first switch arm having a contactengageable with a fixed contact and biased into engagement with saidfixed contact so as to deenergize said heater, and when opened toconnect said heater in the energizing circuit of said toaster, and thesecond and third switch arms carrying cooperating contacts biased apartby the arms and when closed energizing said energizing circuit of saidtoaster and when opened deenergizing it, a spacer between said first andsecond switch arms, manually operable means acting on said first switcharm to move all of said switch arms simultaneously to move the firstaway from its fixed contact and to move the other two together to closetheir contacts, a pivoted latch engageable with said first switch arm tohold it and the other two in said predetermined positions, meansconnecting said latch with said thermostat bar so that when the barmoves responsively to the application of'heat to it by said heater, saidlatch is operated to release said first switch arm to close its contactand thereby deenergize said heater, the latch thereupon engaging anextension on the second switch arm to hold the second and third in theircontact closing positions, and the thermostat bar when cooling inresponse to the deenergization of its heater moving said latch away fromsaid extension to release said second and third switch arms and therebypermit them to open and deenergize said toaster.

10. A thermostatic timing device for controlling the energizing circuitof an electric heater comprising a bimetallic thermostat, heating meansfor applying heat locally to the thermostat, a fixed contact, threesubstantially parallel resilient switch arms, the first biased intoengagement with said fixed contact and the other two carryingcooperating contacts and biased apart, the arms arranged so that whenthe three arms are moved in a predetermined direction to respectivepredetermined positions, the fixed contact is broken by the first armand the two contacts on the other two arms are moved into engagement,connections between said fixed contact, switch arms and energizingcircuit and heating means arranged so that when said arms are moved tosaid predetermined positions, said energizing circuit and said heatingmeans are energized, a latch for holding said arms in said predeterminedpositions, means connecting said latch and said bimetallic thermostatcontrolling the movement of said latch so that when the i thermostat hasbeen heated to substantially a predetermined high temperature the latchreleases said first arm to close said fixed contact, said electricalconnections arranged to deenergize said heating means when said contactis closed, and said last named means operating the latch to release saidother two switch arms to permit them to open their contacts todeenergize said energizing circuit when said thermostat has cooledsubstantially to a predetermined low temperature.

11. A thermostatic timing device for an electric heater having anenergizing circuit comprising, a thermostat, heating means for applyingheat locally to the thermostat, a fixed contact, three substantiallyparallel resilient switch arms, the first biased into engagement withsaid fixed contact and the other two carrying cooperating contacts andbiased apart, the arms arranged so that when the three arms are moved ina predetermined direction to respective predetermined positions, thefixed contact i broken by the first arm and the two contacts on theother two arms are moved into engagement, connections between said fixedcontact, switch arms and energizing circuit and heating means arrangedso that when said arms are moved to said predetermined positions, saidenergizing circuit and said heating means are energized, a latchengaging said first switch arm to hold it in its said predeterminedposition, and said first switch arm engaging one of the other two switcharms and holding them in their said predetermined positions, a leverconnected to said latch and said bimetallic thermostat controlling themovement of said latch so that when the thermostat has been heated tosubstantially a predetermined high temperature the latch releases saidfirst arm to close said fixed contact, said electrical connectionsarranged to deenergize said heating means when said contact is closed,the latch thereupon engaging said one of said other two switch arms tohold them in their said other positions, and said latch operated by saidthermostat when it has cooled substantially to a predetermined lowtemperature to a position wherein it is received in an aperture providedfor it in said one of said other two switch arms to release them topermit them to open their contacts to deenergize said circuit.

12. A timing device for controlling the energizing circuit of anelectrically heated device comprising a thermostat, a heater forapplying heat to said thermostat, a switch mechanism controlling saidenergizing circuit and heater to energize them and deenergize them, apivoted latch associated with said switch mechanism to control itsoperation to latch it in its operative position to energize said circuitand said heater, an arm connected to said latch, a lever having one endconnected to said thermostat and carrying on its other end a surfaceengaging said arm so that when the thermostat is heated it moves thelever to operate the arm and the latch to effect an operation of saidswitch mechanism to deenergize the heater, whereupon said thermostatcools, and when it moves responsively to cooling the lever is movedthereby to operate the arm and latch to effect an operation of theswitch mechanism to deenergize said circuit, and means for varying theposition of said lever to vary the relation of its surface to said arm.

NICHOLAS MILLER.

CERTIFICATE OF CORRECTION Patent No. 2,250,997. July 29, 191 1.

NICHOLAS MILLER.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 5, for 'v'wtih" read --with--; page 3, first column,line 15, for "intervals" read --interva l--; page )4, second column,line 62 claim 8, strike out the word "respective" and insert. the samebefore "predeterminedfin line 65, same claim; and that the said LettersPatent should be read with this correction therein that the same mayconform to the record of the case in the Patent Office. I I

Signed and sealed this 50th day of September, A. D. 191,11.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTI 0N Patent No. 2,2 0,997. July 29, 191 1.

NICHOLAS MILLER.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 5, for 'v'wtih" read -with-; page 5, first column,line 14.}, for "intervals" read --interva l--; page 11., second column,line 62; claim 8, strike out the word "respective" and insert. the samebefore "predetermined'fin line 65, same claim; and that the said LettersPatent should be read with this correction therein that the same mayconform to the record of the case in the Patent Office. i

Signed and sealed this 50th day of September, A. D. 19in.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

